#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<assert.h>
char* my_strcat(char* p1, const char* p2)
{
	assert(p1 != NULL && p2 != NULL);
	char* tmp = p1;
	while (*p1)
		p1++;
	while (*p2)
	{
		*p1 = *p2;
		p1++;
		p2++;
	}
	return tmp;
}
int main()
{
	char a[20] = "abcd";
	char b[] = "efgh";
	printf("%s\n", my_strcat(a, b));
	char c[20] = "abcd";
	char d[] = "efgh";
	printf("%s\n", strcat(c, d));
	return 0;
}